Aqueous borohydride compositions

ABSTRACT

An aqueous fuel for generating hydrogen includes alkaline aqueous composition of about 17 to 37 mole percent of a sodium borohydride, and from about 0.001 to 1 mole percent of sodium hydroxide.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related to U.S. Provisional ApplicationSerial No. 60/337,878, filed Nov. 13, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to aqueous borohydridecompositions, and its use as a hydrogen-based fuel, processes forconverting such fuel into energy, and its use in purification of organiccompounds, recovery of heavy and precious metals and de-colorization ofwastewater streams, synthesis of pharmaceutical compounds, and thegeneration of sodium hydrosulfite in paper, leather and textilemanufacture.

[0004] 2. Brief Description of the Related Art

[0005] Fuel cells are known as a source of energy. Various types of fuelcells are known, including proton exchange membrane, molten carbonate,alkaline, phosphoric acid, and solid oxide. While technologies such asdirect methanol processes have been investigated, such cells frequentlyemploy hydrogen gas as a source of chemical energy, and convert thatchemical energy into electricity for use in powering electricmotor-driven vehicles and the like. The hydrogen gas may be obtainedfrom water by electrolysis at a production facility, stored, and thentransferred as a fuel to vehicles, and stored, for example, under highpressure in a suitable tank. This process has the obvious potentialdisadvantage of having to store quantities of hydrogen, a highlyflammable material. Alternatively, the hydrogen gas can be generated insitu from another material. For example, hydrogen gas can be generatedfrom natural gas using an on-board reformer, or from common gasolineusing an autothermal reformer that extracts hydrogen from gasoline in aseries of chemical conversion steps. In addition to organic compoundssuch as gasoline, another possible source of hydrogen are inorganichydrogen compounds, such as metal hydrides. One example is sodiumborohydride NaBH₄. As an aqueous solution in a fuel cell, sodiumborohydride reacts with water to liberate hydrogen in the presence of asuitable catalyst:

NaBH₄+2H₂O=NaBO₂+4H₂

[0006] In conventional practice, an aqueous solution containing about20% sodium borohydride and about 5% caustic soda in water is used as apropellant. This fuel is stable for a reasonable period of time;however, the high concentration of caustic in the conventionalformulation shortens the effective life of the ruthenium catalyst, andcreates environmental problems associated with the disposal or recycleof the spent sodium borohydride fuel formulation. In addition, the highpH fuel may adversely affect catalysts employed in decomposing thesodium borohydride to provide hydrogen or for the reaction of hydrogenwith a suitable oxidant. It is clear, therefore, that the industry needsa safer, more efficient and more environmentally friendly propellantthan the one offered by the conventional formulation. Thus, while fuelcell-related technology has rapidly progressed recently, there is acontinuing need for stable, high quality fuels for use in such cells.

[0007] Sodium dithionite, also known as sodium hydrosulfite, isspontaneously ignitable and hence considered a hazardous material totransport. Nevertheless, sodium hydrosulfite is used in large quantitiesin the papermaking and textile industries. To avoid transporting sodiumhydrosulfite, in recent years in situ preparation of sodium hydrosulfitefrom the reaction of sodium borohydride, sodium hydroxide solution andsodium bisulfite has been employed. Sodium borohydride is thus widelyemployed in the papermaking and textile industries to prepare sodiumhydrosulfite, such as disclosed, for example, in U.S. Pat. No.5,094,833, herein incorporated by reference. However, solid sodiumborohydride is itself a pyrophoric material, which militates against itsuse in industrial processes. On the other hand, conventional aqueoussolutions of sodium borohydride are not pyrophoric, but tend to havevery limited stability unless stabilized with a caustic material. Thewater of solution disadvantageously increases the cost of shippingborohydride, while the caustic employed for stabilization requiresadditional steps for post-treatment disposal. Thus, there is a need fora stable, low alkaline liquid form of sodium borohydride in manyconventional applications where sodium borohydride is used todayincluding recovery of heavy and precious metals, purification of organicalcohols and amines, synthesis of pharmaceutical compounds, and thegeneration of sodium hydrosulfite for the textile, leather and paperindustries.

SUMMARY OF THE INVENTION

[0008] It is an object of this invention to provide a stable, moreefficient fuel formulation that is consistently higher in alkali metalborohydride concentration than the conventional formulation presentlyused. It is a further object of this invention to provide a fuelformulation that minimizes the use of caustic soda to stabilize thealkali metal borohydride present in the aqueous formulation thereforeincreasing efficiency of the catalyst and presenting no environmentaldisposal problems for the spent fuel. Another object of the presentinvention is to provide a stable, high concentration solution or slurryof alkali metal borohydride. Another object of the present invention isto provide a high concentration solution or slurry of alkali metalborohydride that can be used in existing commercial applications forsodium borohydride including but not exclusive to the recovery of heavyand precious metals, dye wastewater de-colorization, purification oforganic compounds such as alcohols and amines, the production ofhydrosulfite, for use in papermaking, leather and/or textile processing,and processes employing such solutions and slurries. These objectivesare realized by an alkaline aqueous solution according to the presentinvention.

[0009] The present invention provides an aqueous solution and fuel foruse in fuel cells, internal combustion engines and batteries, and aprocess for using that aqueous fuel, such as for transportation andpower generation. More particularly, the present invention provides anaqueous composition comprising a combination of a high concentration ofalkali metal borohydride, preferably sodium borohydride, and a low levelof caustic soda. The present invention provides a stable, low alkalinesolution that is more effective, safer and environmentally preferable toconventional formulations containing lower borohydride concentrationsthat must be stabilized with high caustic concentrations for stability.The present invention provides an alkaline aqueous composition forpropelling fuel cells, internal and external combustion engines,batteries, and for traditional commercial applications where sodiumborohydride is used such as recovery of heavy and precious metals,wastewater de-colorization, purification of organic compounds, synthesisof pharmaceuticals and the production of sodium hydrosulfite, theaqueous composition being comprised of alkali metal borohydride,preferably sodium borohydride, caustic and water, which is high inborohydride concentration, and low in caustic concentration.

[0010] Surprisingly, weakly alkaline, highly concentrated solutions ofsodium borohydride exhibit an acceptable level of stability for use asan aqueous fuel. The alkaline aqueous compositions of the presentinvention are extremely stable under both aerobic and anaerobicconditions, and use of such fuels generate no significant by-productsthat must be disposed of as hazardous waste.

[0011] Preferably, the aqueous composition of the present inventioncomprises an alkaline aqueous solution or slurry comprising from about17 to 37 mole percent of sodium borohydride, and from about 0.001 to 1mole percent of a strong base. More preferably, the aqueous compositionof the present invention comprises an alkaline aqueous solution orslurry comprising from about 24 to 30 mole percent of sodiumborohydride, and from about 0.025 to 0.3 mole percent of a strong base,such as caustic soda. It is especially preferred that the aqueouscomposition of the present invention comprise about 44.0 percent byweight sodium borohydride, about 0.2 percent by weight caustic soda andabout 55.8 by weight water by weight. In terms of mole percent, theconcentrated alkaline aqueous solution preferably comprises about 27.27mole percent sodium borohydride, about 0.12 mole percent sodiumhydroxide, and about 72.61 mole percent water, the mole ratio of sodiumhydroxide to sodium borohydride being about 0.0043.

[0012] Preferably, the aqueous composition of the present inventioncomprises an aqueous slurry having a temperature of from about 10 toabout 30 degrees C.

[0013] The present invention also provides a process for preparing anaqueous solution of sodium hydrosulfite. The process for preparing theaqueous solution of sodium hydrosulfite comprises providing a firstcomponent comprising an aqueous composition comprising sodiumborohydride and sodium hydroxide, a second component comprising sodiumbisulfite, a third optional component comprising sulfuric acid, andmixing the components. Alternatively, caustic and sulfur dioxide can besubstituted for the sodium bisulfite component. The aqueous compositioncomprises from about 17 to 37 mole percent of an alkali metalborohydride, and from about 0.001 to 1 mole percent of sodium hydroxide,and more preferably, from about 24 to 30 mole percent of sodiumborohydride, and from about 0.025 to 0.3 mole percent of sodiumhydroxide.

BRIEF DESCRIPTION OF THE DRAWING

[0014]FIG. 1 is a process flow diagram schematically showing processesfor the preparation of aqueous alkaline compositions according thepresent invention.

[0015]FIG. 2 is graphical representation showing the stability of acomposition according to the present invention.

DETAILED DESCRIPTION

[0016] The alkaline aqueous compositions of the present invention arefluid compositions, taking the form of aqueous slurries or aqueoussolutions. The alkaline aqueous compositions of the present inventioncomprise an alkali metal borohydride, preferably selected from the groupconsisting of lithium borohydride, sodium borohydride, and potassiumborohydride. Sodium borohydride is especially preferred.

[0017] The alkaline aqueous compositions of the present invention areextremely stable under aerobic and anaerobic conditions, and contain alow level of alkaline by-products or stabilizing agents, which mayotherwise be considered as hazardous waste.

[0018] The alkaline aqueous compositions of the present invention can beprepared in a conventional manner. For example, the sodium borohydridesolid material can be dissolved in the prescribed caustic and water toproduce the fuel.

[0019] Alternatively, the composition can be produced by concentratingaqueous sodium borohydride solutions followed by the addition of causticsoda and water. For example, a 12% by weight alkaline aqueous solutionof sodium borohydride and caustic is concentrated by batch mixing the12% w/w product with isopropylamine in a continuous flow solventextraction column to separate sodium borohydride from caustic and waterto make a 6.0% sodium borohydride solution in isopropylamine. Suitableamounts of DI water and the 12% w/w aqueous alkaline solution of sodiumborohydride and caustic are then added back to the sodiumborohydride/isopropylamine to provide a concentrated alkaline solutionof sodium borohydride in a mixed solvent of water and isopropylamine.Finally, the sodium borohydride solution is concentrated by evaporatingthe isopropylamine by conventional means.

[0020] The alkaline aqueous compositions of the present invention can beprepared by the process of the present invention, such as schematicallyshown in the process flow diagram of FIG. 1. In the process of thepresent invention, a feedstock of a dilute alkaline aqueous solution ofsodium borohydride 10, such as an aqueous solution comprising from about6% w/w to about 20% w/w sodium borohydride, is concentrated by mixingthe dilute alkaline solution of sodium borohydride 10 with a polar,non-aqueous solvent 12, such as isopropylamine, that is a good solventfor the sodium borohydride but a poor solvent, or non-solvent for thebase, in a mixing device 12 in order to extract sodium borohydride fromthe alkaline aqueous solution into the non-aqueous phase 16, leaving asodium hydroxide-containing aqueous phase. The non-aqueous phase 16comprising an initial non-aqueous solution of sodium borohydride is thenseparated from the aqueous phase. The initial non-aqueous solution ofsodium borohydride can then be concentrated to provide a predefinedconcentration of sodium borohydride by evaporating the non-aqueoussolvent, such as by a vacuum evaporative technique or step, in asuitable evaporating device 20. Predefined amounts of water 24 and analkaline stabilizing agent 26, such as sodium hydroxide, can then beadded to the concentrated non-aqueous solution of sodium borohydride 22in a mixing device 28. Preferably, the alkaline stabilizing agentcomprises additional feedstock, which is relatively enriched in sodiumhydroxide. The resulting mixture 30 can then be transferred to suitableevaporation device 32, and the remaining non-aqueous solvent can beremoved, to provide the concentrated product 34. The gaseous stream ofnon-aqueous solvent 36 is condensed in a suitable condenser 38 toprovide liquid non-aqueous solvent 40 that can be recycled in theprocess. Alternatively, predefined amounts of water 50, such asdistilled (Dl) water and an alkaline stabilizing agent 52, preferablycomprising the feedstock, can be mixed in a suitable mixing device 54with the initial non-aqueous solution of sodium borohydride 16, and theresulting solution 56 can then be concentrated by evaporating thenon-aqueous solvent in a suitable evaporating device 58 to provide analkaline aqueous composition having predefined concentrations of sodiumborohydride and stabilizing agent 60, with the resulting gas-phasenon-aqueous solvent 62 being condensed in a suitable condensing device64 so that the liquid non-aqueous solvent 66 can be recycled.

[0021] The present invention provides a process for energizing fuelcells, internal and external combustion engines, and batteries fortransportation and energy generation. The process of the presentinvention comprises providing an alkaline aqueous solution of thepresent invention as a source of hydrogen to a suitable device fordecomposing the sodium borohydride, and using the liberated hydrogen asa source of energy. For example, decomposition of the sodium borohydridecan be accomplished chemically, with a suitable catalyst, such asruthenium, to produce hydrogen that is ignited in either an internal orexternal combustion engine. In addition, the alkaline aqueous solutioncan be provided to a fuel or battery in which the decomposition ofsodium borohydride can be accomplished at the anode.

[0022] Further, the sodium borohydride solution of the present inventioncan be employed in the reduction of sodium bisulfite to generate sodiumhydrosulfite for use in textile processing, leather and papermaking,such as disclosed for example, in U.S. Pat. No. 4,788,041, herebyincorporated herein by reference. Conventionally, a solution of 12%sodium borohydride and 40% sodium hydroxide is used. In the process ofthe present invention, a first component comprising an aqueouscomposition comprising sodium borohydride and sodium hydroxide, a secondcomponent comprising sodium bisulfite solution, and an optional thirdcomponent comprising sulfuric acid are provided, and the components aremixed, thus generating the aqueous sodium hydrosulfite. Optionally, amixture of sulfur dioxide and caustic can be substituted for the sodiumbisulfite solution in order to generate the bisulfite in situ. Theaqueous borohydride composition used in this process comprises fromabout 17 to 37 mole percent of an alkali metal borohydride, and fromabout 0.001 to 1 mole percent of sodium hydroxide, and more preferably,from about 24 to 30 mole percent of sodium borohydride, and from about0.025 to 0.3 mole percent of sodium hydroxide.

[0023] Employing a sodium borohydride solution according to the presentinvention advantageously reduces transportation costs, since, forexample, a 44% solution is almost four times the strength of thetraditional formulation making it much less expensive to transport. Inaddition, in the conventional process the 40% caustic must beneutralized with acid for the sake of efficiency. The 44% solutioncontains almost no caustic, thus reducing or eliminating the capital andmaterial costs associated with the use of acid.

[0024] Because solid sodium borohydride is pyrophoric, the concentratedsolution of the present invention advantageously provides anon-pyrophoric concentrated source of sodium borohydride for use invarious environmental, organic chemical, pharmaceutical and electronicapplications.

[0025] The following examples are provided to better disclose and teachprocesses and compositions of the present invention. They are forillustrative purposes only, and it must be acknowledged that minorvariations and changes can be made without materially affecting thespirit and scope of the invention as recited in the claims that follow.

EXAMPLE 1

[0026] Sodium borohydride solution (12% w/w sodium borohydride, 40% w/wsodium hydroxide, and 48% w/w water) and isopropylamine (IPA) are feedinto a counter current extraction column in a ratio of approximately twoparts by volume of IPA and one part sodium borohydride solution. Thesodium borohydride is dissolved into the IPA and flows out the top ofthe extractor while the sodium hydroxide and water flows out the bottom.The IPA/sodium borohydride solution contains approximately 6% sodiumborohydride and only a few tenths of a percent sodium hydroxide. TheIPA/sodium borohydride solution is then directed to an evaporator toremove IPA from the solution, and the IPA/sodium borohydride solution isconcentrated to a point where the sodium borohydride solution isvirtually free of IPA. The concentrated sodium borohydride solution isthen sent to a mixing tank. In the mixing tank the concentrated sodiumborohydride solution, water and a 12% w/w aqueous sodium borohydridesolution are combined to the proper ratio to produce the 44% w/w sodiumborohydride, 0.2% w/w sodium hydroxide and 55.8% w/w water. Theresulting solution is then optionally processed through a finalevaporator to remove residual IPA from the solution.

EXAMPLE 2

[0027] Alkaline aqueous sodium borohydride solutions were prepared inthe proportions shown in Table A below using sodium hydroxide as thecaustic material. The solutions were stored at the temperature shown inTable A, and the decomposition rate of the sodium borohydride wasdetermined by hydrogen evolution. The resulting decomposition rates arealso shown in Table A. The results reported in Table A show that a 44%w/w solution of sodium borohydride is stabilized against decompositionby a surprisingly low level of caustic. TABLE A Decomposition AqueousSolution Temperature Rate % NaBH₄ % Caustic Deg C. % NaBH₄/hr. 12.0 40.025.0 0.00 9.3 0.0 25.0 2.50 9.3 0.5 25.0 0.30 44.0 0.0 40.0 0.06 44.00.1 40.0 0.01 44.0 0.2 40.0 0.00 47.0 0.7 50.0 0.03 47.0 1.0 50.0 0.0250.0 0.3 60.0 0.17 50.0 0.5 60.0 0.10 50.0 0.7 60.0 0.03

EXAMPLE 3

[0028] Samples of the 44% sodium borohydride solution prepared accordingto the process of Example 1 are stored at 25 degrees C. for the periodsindicated in Table B. The concentration of sodium borohydride in thesample is determined either by the titration method or by evolution ofhydrogen, using a modification of the test procedure of Davis, W. D.;Mason, L. S.; Stegeman, G., J. American Chemical Society 1949, 71, 2775;and the results are reported in Table B and graphed in FIG. 1. Theresults reported in Table B and displayed in FIG. 1 show that the 44%sodium borohydride solution surprisingly retains about 90 percent of itsinitial activity, even after almost a year of storage. TABLE B WeightPercent Method Time Elapsed Sodium Borohydride (Titration/Evolution)(Days) 43.21% T 0 44.60% T 35 44.70% T 35 43.60% T 76 43.10% T 76 41.33%E 76 42.83% E 85 41.79% E 85 42.50% E 98 43.20% E 98 41.86% E 132 41.83%E 132 41.37% E 176 41.45% E 176 39.96% E 272

EXAMPLE 4

[0029] A 44% w/w sodium borohydride solution is produced by extractingsodium borohydride (SBH) from a commercially available sodiumborohydride solution (Boromet 1240, Montgomery Chemical, Conshohocken,Pa.) with an isopropylamine (IPA) and water solution. The extracted SBHin solution is recombined with the appropriate amount of water andBoromet 1240 so that when all the IPA is removed the resulting productis a high concentration sodium borohydride solution (“Borojet 442”) ofthe following make-up:

[0030] 44% w/w sodium borohydride

[0031] 0.2% w/w sodium hydroxide

[0032] Balance water

[0033] Four trials of laboratory scale implementation of this processwere conducted as follows:

[0034] An IPA extraction solution was prepared by combining IPA andwater to yield an 88% w/w IPA solution. This solution was then used toextract SBH from Boromet 1240. The IPA solution was mixed with Boromet1240 in a separatory funnel in a 2 to 1 volumetric ratio; 2 parts IPAsolution per 1 part Boromet 1240. Two phases formed. The heavy phase, acaustic water solution, was drawn off and set aside. The light phase,the extracted SBH in IPA, was collected and analyzed by an iodatetitration procedure.

[0035] The SBH content in each of the IPA extractions were found to be:% w/w SBH in IPA Trial Extraction Solution A1 7.30% w/w B1 6.44% w/w C19.30% w/w D1 6.89% w/w

[0036] Using the analysis, and weight of each sample, the mass of SBHpresent in each sample was calculated. Sample calculations from Trial D1are as follows:

(Sample weight)×(% w/w SBH)=mass SBH

(70.245 g)×(6.89%)=4.84 g SBH

[0037] The amount of water and Boromet 1240 needed, to yield the desiredBorojet 442 composition, is calculated as follows:

(4.84 g SBH)/(44% SBH)=11.0 g Borojet 442

(11.0 g Borojet 442)(0.2% w/w NaOH)=0.022 g NaOH

(0.022 g NaOH)/(40% w/w NaOH)=0.055 g Boromet 1240

[0038] Thus, 0.055 g of Boromet 1240 are to be added to the extractedSBH in IPA solution to provide the necessary NaOH content. Note: becauseSBH and water are also present in Boromet 1240, their contribution tothe final product must to be considered when carrying out the process ona larger scale. However, because small quantities were employed in thesetrials, SBH and water contributions due to the Boromet 1240 can beconsidered negligible, as it is shown here:

(0.055 g Boromet 1240)×(12% w/w SBH)=0.007 g SBH

[0039] The amount of water required is calculated to be:

11.0 g Borojet 442−4.84 g SBH−0.055 g Boromet 1240=6.105 g water

[0040] The extracted SBH in IPA, Boromet 1240 and water are combined andreanalyzed for SBH content, again by iodate titration. The results wereas follows: % w/w SBH in IPA Trial after recombination A1 6.87% w/w B16.32% w/w C1 6.64% w/w D1 6.48% w/w

[0041] Each sample was then placed in a simple distillation apparatus toremove the IPA and any excess water. This could be accomplished byvarious methods, but for the purpose of these experiments the simpledistillation method was used. The samples were placed under vacuum andheated.

[0042] Trials A2 and B2 were performed at 15 in Hg vacuum. The sampleswere placed under heat and the IPA was removed and collected bycondensing the vapor. Because the actual weight of the desired productis known, the samples would be periodically removed from the apparatusand weighed, in the same boiling flask of known weight until enough IPAand excess water had been removed. When it was believed that the IPA andexcess water was removed, based on the sample weight, the product wasanalyzed for SBH concentration by iodate titration. The results were asfollows: % w/w SBH in Trial Concentrate A2 40.7% w/w B2 39.7% w/w

[0043] Having a better understanding of how the IPA removing stepphysically occurs, Trials C2 and D2 were performed. Trials C2 and D2were initiated under moderate vacuum to prevent extreme flashing of theIPA. Temperature and amount of vacuum were recorded over time and as thetemperature increased the amount of vacuum was increased to preventoperating at elevated temperatures. The following is data recorded fromTrial C2: Vacuum Time Temp. (C.) (in Hg) 8:30 23 17 8:36 26 17 8:38 2815 8:51 36.5 15 9:03 42 15 9:13 50 15 9:23 85 15 9:32 96 15 9:45 99 159:47 81 25 10:06  90 25

[0044] At time 10:06 a sample was analyzed by iodate titration and foundto be 32.95% w/w SBH. However, this analysis was believed to beinaccurate for two reasons. First when the sample was weighed it wasfound that an additional 1.1 g of water was removed from the sample andsecond, the sample was in crystalline form. At 90° C. a Borojet 442solution should be in liquid form. Both of these observations indicatethat the sample should be over-concentrated and have a SBH concentrationgreater than 44% w/w.

[0045] The analysis was then repeated by hydrogen evolution and the SBHconcentration was found to be 46.4% w/w. It is believed that the iodatemethod, as the procedure is presently performed and which was originallydeveloped to analyze Boromet 1240, is unable to accurately detect thehigh level of SBH in Borojet 442.

[0046] A Borojet 442 sample has approximately 3.7 times as much SBH perunit of mass as does a Boromet 1240 sample. The iodate procedure remainsa viable method of analysis for lower concentrations of sodiumborohydride; another method should be used for higher concentrations.Thus, although Trial A2 and Trial B2 yielded SBH concentrations of 40.7and 39.7% w/w in the final product using the iodate method, it is nowbelieved these analyses cannot be considered accurate because the iodateanalysis procedure was employed.

[0047] Trial D2 was then performed following the same procedure butknowing that the proper concentration will be achieved at 25 in Hg ofvacuum and at a temperature less than 90° C. The data for Trial D2 arefollows: Temp. Vacuum Time (C.) (in Hg.) 1:44 23 16 1:51 29 16 1:57 3416 2;05 41 18 2:11 51 18 2:16 73 21 2:19 89 21 2:21 84 23 2:26 80 252:30 84 25 2:34 86 25

[0048] At time 2:34 the sample was removed, weighed and analyzed. Thesample weight suggests that the concentration of SBH should be slightlyhigher than 44% w/w. The SBH concentration was found to be 44.5% w/w byhydrogen evolution. A calculation to determine mass of SBH shows that4.80 g of SBH is present in the sample. When compared to the amount ofSBH to start it is found that 0.8% of the SBH appears lost in theprocess:

[(4.84−4.80)14.84]×100%=0.83%

[0049] Various modifications can be made in the details of the variousembodiments of the processes, compositions and articles of the presentinvention, all within the scope and spirit of the invention and definedby the appended claims.

We claim:
 1. An aqueous fuel for generating hydrogen, the aqueous fuelcomprising an alkaline aqueous composition comprising from about 17 to37 mole percent of an alkali metal borohydride, and from about 0.001 to1 mole percent of a strong base.
 2. An aqueous fuel according to claim1, the alkaline aqueous composition comprising from about 24 to 30 molepercent of sodium borohydride, and from about 0.025 to 0.3 mole percentof a strong base.
 3. An aqueous fuel according to claim 2, the strongbase being selected from alkaline metal and alkaline earth metalhydroxides.
 4. An aqueous fuel according to claim 3, the alkaline metalhydroxide being sodium hydroxide.
 5. An aqueous fuel according to claim1, the alkaline aqueous composition comprising 44.0 percent by weightsodium borohydride, 0.2 percent by weight caustic soda and 55.8 byweight water by weight.
 6. An aqueous fuel according to claim 4, thealkaline aqueous composition comprising about 27.27 mole percent sodiumborohydride, about 0.12 mole percent sodium hydroxide, and about 72.61mole percent water.
 7. An aqueous fuel according to claim 1, the moleratio of base to sodium borohydride being about 0.0043.
 8. An aqueousfuel according to claim 1 having a temperature from about 10 degrees C.to about 30 degrees C.
 9. An aqueous fuel according to claim 1 furthercomprising an effective amount of a viscosity-reducing additive.
 10. Anaqueous fuel according to claim 9 wherein the additive is selected fromthe group consisting of isopropyl alcohol, ethylene glycol,2-ethylhexanol, and sodium chloride.
 11. An aqueous fuel according toclaim 10 wherein the additive comprises about 1.4% w/w isopropylalcohol.
 12. A process for energizing fuel cells, batteries, internaland external combustion engines for transportation and power generation,the process comprises providing an alkaline aqueous solution as a sourceof hydrogen or protons to a suitable device for decomposing the sodiumborohydride, and using the liberated hydrogen as a source of energy, thealkaline aqueous composition comprising from about 17 to 37 mole percentsodium borohydride, and from about 0.001 to 1 mole percent of a strongbase.
 13. A process according to claim 12 wherein decomposition of thesodium borohydride is accomplished chemically with a suitable catalystto produce hydrogen.
 14. A process according to claim 13 furthercomprising igniting the hydrogen in an internal or external combustionengine.
 15. A process according to claim 13 wherein the catalyst isruthenium or other suitable catalyst.
 16. A process according to claim12, the alkaline aqueous composition comprising from about 24 to 30 molepercent of sodium borohydride, and from about 0.025 to 0.3 mole percentof a strong base.
 17. A process according to claim 16, the strong basebeing selected from alkaline metal and alkaline earth metal hydroxides.18. A process according to claim 17, the alkaline metal hydroxide beingsodium hydroxide.
 19. A process according to claim 12, the alkalineaqueous composition comprising 44.0 percent by weight sodiumborohydride, 0.2 percent by weight caustic soda and 55.8 by weight waterby weight.
 20. A process according to claim 18, the alkaline aqueouscomposition comprising about 27.27 mole percent sodium borohydride,about 0.12 mole percent sodium hydroxide, and about 72.61 mole percentwater.
 21. A process according to claim 12, the mole ratio of base tosodium borohydride being about 0.0043.
 22. A process according to claim12, the alkaline aqueous composition having a temperature from about 10degree C. to about 30 degrees C.
 23. A process according to claim 12,the alkaline aqueous composition further comprising an effective amountof a viscosity-reducing additive.
 24. A process according to claim 23wherein the additive is selected from the group consisting of isopropylalcohol, ethylene glycol, 2-ethylhexanol, and sodium chloride.
 25. Aprocess according to claim 24 wherein the additive comprises about 1.4%w/w isopropyl alcohol.
 26. A process for preparing an alkaline aqueousborohydride composition, the process comprising: a) mixing a feedstockof a dilute alkaline aqueous solution of sodium borohydride with apolar, non-aqueous solvent that is a good solvent for the sodiumborohydride but a poor solvent, or non-solvent, for the base; b)extracting sodium borohydride from the alkaline aqueous solution intothe non-aqueous phase; c) separating the non-aqueous solution of sodiumborohydride from the aqueous phase; d) concentrating the initialnon-aqueous solution of sodium borohydride to provide a predefinedconcentration of sodium borohydride by evaporating the non-aqueoussolvent; and e) adding a predefined amount of an alkaline stabilizingagent to the concentrated non-aqueous solution of sodium borohydride toprovide a product.
 27. A process according to claim 26 wherein thealkaline stabilizing agent comprises additional feedstock.
 28. A processaccording to claim 27, wherein the product includes residual non-aqueoussolvent and further comprising separating residual non-aqueous solventfrom the product to provide a concentrated product.
 29. A process forpreparing an aqueous solution of an sodium hydrosulfite, the processcomprising: a) providing a first component comprising an aqueouscomposition comprising an alkali metal borohydride and sodium hydroxide;b) providing a second component selected from the group comprising (i)sodium bisulfite, and (ii) sulfur dioxide and caustic; c) optionallyproviding a third component comprising sulfuric acid; d) mixing thecomponents; wherein the aqueous composition comprises from about 17 to37 mole percent of an alkali metal borohydride, and from about 0.001 to1 mole percent of sodium hydroxide.
 30. A process according to claim 29,wherein the aqueous composition comprises from about 24 to 30 molepercent of sodium borohydride, and from about 0.025 to 0.3 mole percentof sodium hydroxide.